The encapsulation of local anesthetics in liposomes allowed the manipulation of some pharmacological properties of these agents improving their therapeutic effects. Objectives: To compare the in vitro effects of plain and liposomal bupivacaine on the modulation of the proinflammatory cytokines IL-6, IL1-alpha, IL-8 and TNF-alpha. The cytotoxicity of the same formulations was also addressed in human keratinocytes culture. Methods: Human keratinocytes (HaCaT) were grown in DMEM medium supplemented with 10% heat-inactivated FBS and 50 µg/mL gentamicin. The cells were exposed to plain or liposomal 100 µM, 10 µM and 1 µM bupivacaine for 6 and 24 hours. Cytokines quantification was performed by ELISA and cell viability was estimated using XTT assay. Results: Bupivacaine at all concentrations significantly reduced IL-6, IL1-alpha and TNF-alpha release (p<0.05, Kruskal-Wallis). However, it stimulated a significant increase of IL-8 release after 6 hours (p<0.05, Kruskal-Wallis). Liposomal encapsulation was able to significantly reduce the IL-8 release when compared with the plain formulation (p<0.05, Kruskal-Wallis). The cell viability (%) results are show in the table.
Time | Control group | Plain bupivacaine | Liposomal bupivacaine | ||||
100 µM | 10 µM | 1 µM | 100 µM | 10 µM | 1 µM | ||
6h | 100 | 70.16 | 86.65 | 76.38 | 75.63 | 73.21 | 63.31 |
24h | 100 | 63.86 | 79.98 | 90.31 | 89 | 85.73 | 98.12 |
Conclusions: Liposomal encapsulation showed little interference on the bupivacaine immunoregulatory and cytotoxic properties. However, it was able to reduce IL-8 release and decreased the toxicity on human keratinocytes when compared to the plain bupivacaine at 100 µM concentration after 24 hours.